大牛地气田上古生界压力封存箱与储层孔隙演化  

PRESSURE COMPARTMENT AND EVOLUTION OF RESERVOIR POROSITY IN THE UPPER PALEOZOIC OF DANIUDI GAS FIELD,ORDOS BASIN,CHINA

作　　者：李仲东[1] 张哨楠[1] 周文[1] 惠宽洋[2] 李良[2] 过敏[1] 范世龙[1] 袁京素[1] 

机构地区：[1]成都理工大学"油气藏地质及开发工程"国家重点实验室,四川成都610059 [2]中国石油化工股份有限公司华北分公司,河南郑州450006

出　　处：《矿物岩石》2007年第3期73-80,共8页Mineralogy and Petrology

基　　金：国家973煤层气项目(2002CB211705)

摘　　要：针对大牛地气田二叠系和石炭系泥岩发育高压封存箱,与之相对应层段的砂岩具异常高孔隙这一现象,通过对砂岩高孔隙段的发育现状、成岩作用特征和不同阶段压力封存箱形成与储层孔隙演化关系进行研究后认为:①砂岩高孔隙发育段主要分布在上、下石盒子组、山西组,层位性强,具可对比性,与相应层段泥岩"欠压实"密切相关;②该区压力封存箱开始发育于砂岩正常压实之前,压力封存箱的形成,极大限制了层内的流体流动,阻碍了砂岩的进一步压实和胶结作用,从而对下石盒子组砂岩原生孔隙的保护有积极作用;③箱内山西-太原组烃源岩有机质成烃的有机酸性水溶蚀对形成次生孔隙最为有利;④晚成岩作用期砂岩内部异常高孔隙压力抑制了成岩作用的发生,使孔隙空间得到了有效保护;⑤烃源岩生烃过程中产生的超高压,引起砂岩破裂形成裂缝,不但增加了储层渗透性,也成为天然气运移的主要通道和成藏动力;⑥由于压力封存箱的封闭,溶蚀的物质不能有效带出系统,溶蚀与充填的消长影响,在盒3、盒2段成藏过程中,气水重力分异,对上部盒3、盒2段成藏有利,但对下部盒1、山1、山2段次生孔隙保存不利,同时对其成藏也有消极影响。Overpressure compartments occurred in the mudstones of Carboniferous-Permian formations in the Daniudi Gas Field and high density porosity zones also appeared in the sandstone in the same reservoirs layers. The detailed study of development situation, characters of diagenesis, the correlation between the formation of pressure compartment and evolution of fissures in the reservoir reached following conclusions： ①High-porosity zones in the sandstone reservoirs were controlled by horizon and mainly distributed in the upper-lower Shihezi Formation and Shanxi Formation. The appearance of high-porosity zones in the sandstone was closely related to the poor compaction of mudstones in the same layers. ②Overpressure compartments developed prior to the normal compaction phase of sandstones in the area. The formation of pressure compartments obviously restricted the migration of liquid within the layers, preventing the further compaction and cementation of sandstones and therefore, playing a favorable role in the protection of primary pores in the sandstones of the Shihezi Formation. ③The dissolution resulted from the organic acids during the formation of hydrocarbon in the pressure compartments of Shanxi Formation and Taiyuan Formation produced favorable conditions for the generation of secondary pores. ④The abnormal high pore pressure in the sandstones during the late diagenesis restricted the development of diagenesis, thus, effectively protecting the pore space. ⑤The formation of ultrahigh-pressure in the process of hydrocarbon evolution resulted in the occurrence of fissures in the sandstones and increased the permeability of reservoir. Ultrahigh-pressure not only provided driving force in the gas accumulation, but also provided passages for migration of gas. ⑥Owing to the closure state of pressure compartment, there existed mutual restriction for the dissolution and infilling because the dissolved materials was unable to move out of the system. The gravity dissemination of gas and water created a favorab

关 键 词：大牛地气田 上古压力封存箱 原生孔隙保存 次生孔隙形成 

分 类 号：TE121.1[石油与天然气工程—油气勘探]